Really good receiver for 14MHz
 

Hello,

I'd like to build a simple receiver for 20m band. Saying "simple" I
don't mean a "starter project" - I've built my first direct conversion
receiver for 3.5 MHz already. I'm looking for something more complicated
than basic DC receiver with 2 transistors + LM386.

My goal is significantly better CW reception - I don't care about SSB.
Is an op-amp filter before amplifier the only method to get good
selectivity in DC receivers? Or maybe I should try a simple superhet?

The most important thing is to choose a good project. I know there are
famous kits like ones from Ten-tec etc., but in my case the costs of
delivery could reach 3/4 of the kit's retail price, so I'd rather go for
a well-established circuit from Internet and build it from the scratch.
Could you recommend me a project that was copied with success by many
hams, designed with the idea of an easy alignment by beginners
i.e. based on "tolerant" circuits without tendency to oscillations and
other surprises ?

thanks in advance,

(Julian Vereker) wrote in message . com...

I'd like to build a simple receiver for 20m band. Saying "simple" I
don't mean a "starter project" - I've built my first direct conversion
receiver for 3.5 MHz already. I'm looking for something more complicated
than basic DC receiver with 2 transistors + LM386.

if you already have a DC receiver, all you need to do is add a simple
ladder filter to the input of the DC receiver, add a mixer to the
otherside and a VFO. You will have a pretty decent superhet. Don't
throw away the DC receiver, just build up a superhet around it.

You current VFO can be moved up to being the Local oscillator for the
superhet. Two or three crystal filter at the input of your current
product dectector should provide you with bright quality of filtering.
On the front-end just use a single FET with a post-mix amp. check my
transceiver for the idea at http://farhan.co.net.nr.

The actual receiver that served as the basis of the transceiver is
called S7C by OM Wes Hayward. It is in EMRFD. You should get a copy of
the book if you are serious about understanding and homebrewing.

- farhan

(Julian Vereker) wrote in message . com...

I'd like to build a simple receiver for 20m band. Saying "simple" I
don't mean a "starter project" - I've built my first direct conversion
receiver for 3.5 MHz already. I'm looking for something more complicated
than basic DC receiver with 2 transistors + LM386.

if you already have a DC receiver, all you need to do is add a simple
ladder filter to the input of the DC receiver, add a mixer to the
otherside and a VFO. You will have a pretty decent superhet. Don't
throw away the DC receiver, just build up a superhet around it.

You current VFO can be moved up to being the Local oscillator for the
superhet. Two or three crystal filter at the input of your current
product dectector should provide you with bright quality of filtering.
On the front-end just use a single FET with a post-mix amp. check my
transceiver for the idea at http://farhan.co.net.nr.

The actual receiver that served as the basis of the transceiver is
called S7C by OM Wes Hayward. It is in EMRFD. You should get a copy of
the book if you are serious about understanding and homebrewing.

- farhan

Ashhar Farhan wrote:
[snip]
On the front-end just use a single FET with a post-mix
amp. check my
transceiver for the idea at http://farhan.co.net.nr.

Oops, that's http://farhan.net.co.nr/ and a most interesting write-up.

73, Tom

Ashhar Farhan wrote:
[snip]
On the front-end just use a single FET with a post-mix
amp. check my
transceiver for the idea at http://farhan.co.net.nr.

Oops, that's http://farhan.net.co.nr/ and a most interesting write-up.

73, Tom

if you already have a DC receiver, all you need to do is add a simple
ladder filter to the input of the DC receiver, add a mixer to the
otherside and a VFO. You will have a pretty decent superhet. Don't
throw away the DC receiver, just build up a superhet around it.
As I wrote I have DC RX, but for 3.5 MHz. What I need is monoband for
14 MHz. My RX is very simple and I am not sure if its circuit,
especially the VFO will work well in the higher frequency.

You current VFO can be moved up to being the Local oscillator for the
superhet. Two or three crystal filter at the input of your current
product dectector should provide you with bright quality of filtering.
On the front-end just use a single FET with a post-mix amp. check my
transceiver for the idea at http://farhan.co.net.nr.

Thanks for the link.

jvereker

if you already have a DC receiver, all you need to do is add a simple
ladder filter to the input of the DC receiver, add a mixer to the
otherside and a VFO. You will have a pretty decent superhet. Don't
throw away the DC receiver, just build up a superhet around it.
As I wrote I have DC RX, but for 3.5 MHz. What I need is monoband for
14 MHz. My RX is very simple and I am not sure if its circuit,
especially the VFO will work well in the higher frequency.

You current VFO can be moved up to being the Local oscillator for the
superhet. Two or three crystal filter at the input of your current
product dectector should provide you with bright quality of filtering.
On the front-end just use a single FET with a post-mix amp. check my
transceiver for the idea at http://farhan.co.net.nr.

Thanks for the link.

jvereker

Oooops! I'm not sure but probably I've made a little error writing,
that I wanna buld it "from scratch". Actually I want to brew it FROM
PUBLISHED PLANS. I thought a term "from scratch" doesn't mean
designing&brewing. I just got know (English isn't my first language).

Oooops! I'm not sure but probably I've made a little error writing,
that I wanna buld it "from scratch". Actually I want to brew it FROM
PUBLISHED PLANS. I thought a term "from scratch" doesn't mean
designing&brewing. I just got know (English isn't my first language).

IK3OIL has a 14 MHz QRP rig with schematics and PCB layouts, and if you
build 2
of the 3 PCBs you get a receiver. I think if you put IK3OIL into Google you
will find it.


--
Sverre, LA3ZA
www.qsl.net/la3za


"Julian Vereker" wrote in message
om...
Oooops! I'm not sure but probably I've made a little error writing,
that I wanna buld it "from scratch". Actually I want to brew it FROM
PUBLISHED PLANS. I thought a term "from scratch" doesn't mean
designing&brewing. I just got know (English isn't my first language).